An Etymological Dictionary of the German Language/Annotated/Kohle

Kohle, feminine, ‘coal, charcoal,’ from the equivalent Middle High German kole, feminine, mostly kole, kol, masculine, and kol, neuter, Old High German cholo, masculine, chol, neuter; compare Anglo-Saxon col, neuter, English coal (English colemouse, see under Kohlmeise), Old Icelandic kol, neuter plural, ‘coals.’ Akin to the derivs, Old Icelandic kylna, feminine, ‘kiln,’ Anglo-Saxon cylne, English kiln, as well as Swedish kylla, ‘to heat.’